Thermic



ROBERT AERNOUT BARON VAN LYNDEN. THERMIC TELEPHONE.

APPLICATION HLED MAY 2. 1916.

Lmzm, Pmenfedgug. 5,1919.

lll? /Z j" )anni onirica,

ROBERT AERNOUT BARON VAN LYN'DEN, OF UTRECHT, NETHERLANDS, ASSIGNOR, BY

MESNE ASSIGNMENTS, TO AMERICAN THERMOPHONE COMPANY, 0F BOSTON, MASSA- CHUSETTS, A CORPORATION OF MASSACHUSETTS.

THERMIC TELEPHONE.

Application filed May 2, 1916. Serial No 94,869.

To all whom t may concern:

Be it known that I, ROBERT AnRNoUT BARONY VAN LYNDEN, a subject ofthe Queen of the Netherlands, and residing at Utrecht, in the Netherlands, have. invented new and useful Improvements in Thermlc Telephones, 4'owfln'cli the following 1s a specification.

My invention relates to thermic telephones and has particular reference yto an improved construction of the heating conductors of such apparatus.

According to my invention the heating conductor is of such a nature that, unlike the usual conductor of Wollaston or other wire, it is not capable of standingalone and it is laid, 'or preferably formed, upon a support which is a partial conductor of heat `but is practically a non-conductor of electricity,

that is tosay, the material forming the support, when yused for this" purposepls sufficiently a non-conductor of electrlcl-ty' to prevent the shont-circuiting of the heating conductor which is laid o r formed )upon 1t.

The support'may be of any. suitable material such for example as marble or other stone, china, porcelainr or the like. l n

Theheating conductor may .beumade 1n any convenient way, for instance 1t can he formed of thin metallic sheet or foil laid upon Ithe support to which .it lmay beate.

tached in intimate Contact.

Again the conductor may. be deposited electrolyitically upon the support, the necessary figure or shape-for instance afloop or series of loops-being deposited or a flat sheet or film of the requisite thinness being first deposited and the ligure produced by etching out the portions not required.

Another method of making the conductor according to my invention is to form the figure by drawing, painting or printing upon the support with a sui-table metallic pigment or by tracing the figure upon the suppont with a carbon, black lead or metallic pencil.

The heating conductor made according to my invention is generally fbroad in proportion to its thickness for it is intended to be of extreme thinness and further the com? paratively broad upper surface which is eX- posed to the air in the sound chamber, very quickly gives up its heat 'to that air. On the other hand theunder surface, in intimate contact with the support, which is a partial Specification of Letters Patent.

1 the suraceby chemical or other Patented Ang, 5, i919.

conductor of heat, serves to prevent the heating conductor from accumulating heat and thus keeps practically constant what may be termed the' normal work-.ing temperature'of the apparatus.V

In a modified construction to my invention the support for the heating conductor comprises a body of' some material which is good conductor of heat, for instance a metal, and a. thin layer or coating of some material which i'slpractically a nonconduotor of' electricity but a partial conductor of heat. Upon this surface or coating is lai'd, or preferably formed, tlhe heating conductor itself.

It will beapp-recirated that the function of the thin layer or coating isto insulate elec,- -trically the heating-oonductorfwhile allowing its heart to be `carried away rapidly by the heat-conducting body vforming the main also according y portie-nef the supportai or Vformed upon the body of the support in any convenient way,

for ins-tance the i Suppont may bemade of metall and the layer or coating maybe produced by forming upon film of oxid, sulfid- 'or l other compound which ,is sufciently a non-condutor of elecfftrlcity to prevent the-'short-crcuiting of the heating conductor when laid or formed upony it.

Another method consists metallic support with a thin layer of enamel, varnish or the likev of such Ya nature' as to withstand fthe temperature heating conductor is raised during theoper? ation of the telephone.' 0r, again, ath-in layer or sheet of some suitable mater-iai may be placed" in intimate Contact With,v thev surface of the conducting body forming the support. i Y l v In the accompanying drawings Wfhich are merely intended to illustrate the inventionA diagrammatically,

Figure 1 is an elevation with parts in Sec. tion showing one construction of athermio telephoneZ accordingv to my invention.

v Fig. 2 is a plan showing the heating c0- duotor resting upon its support, and' Fig. 3 is aV vertical central section through a modified construction of supportv for the to which 'theyv means, a

inV coating the heating conductor also according to this inu i to 'a connection cap B 'and holds down av sound chamber C which in its turn rests upon and secures in its place upon the connection cap the support D for the heating conductor.

ln the usual construction of thermic tele-4 phones the heating conductor, made of Wollaston Wire or the like, Wouldbe mounted so as to stand upright upon the support D, but according to this invention the conductor, which is of such a nature that it cannot stand alone, is laid or formed upon the upper surface of the support D. In Fig. 2 the heating conductor is shown at E in the form of an S-shaped ribbon or strip of extreme thinness which is formed upon or laid upon the support D, its ends being secured in electrical contact with terminals or connections F, these-being joined inan well-known or approved manner With the eads G for connection-to the circuit.

It will be understood that the heating conductor 'E maybe of any shape or figure and may be formed upon the surface of the support D in any suitable Way.

The support D shown in Figs. 1 and 2 is,

intended to be made ofsome material'which is a partial conductor of heat but practically a non-conductor of electricity; a substance such as marble for iinstance might be employed.

n Fig. 3 a modied construction of su port for the heating conductor is shown. n this case the main body of the support D1 is of metal and in order to avoid the short circuiting of the heating conductor E which would occur if it were laid or formed directly 'upon the metal surface, a thin layer or coating H is applied to or formed upon the surface of the' support D1 and on this layer or coating H the heating conductor E isformed or laid, said coating H therefore' forming the immediate support of the conductor E. As in the construction illustrated in Figs. 1 and 2 the ends of the heating conductor E are joined to terminals F but these terminals must necessarily be insulated as they pass through the metallic block D?. For this urpose insulating sleeves or bushes F1 and lnsulating Washers F2 are provided.

The layer or coating H may be of any substance Which is suicienthv' a non-conductor of electricity as to preventthe short-circuit ing of the heating conductor E and in some cases the upper surface of the metal block Dv may be tarnished heavily, for instance a coating of oXid or suld may be given which Will suflice for the purpose.

I claim as myinvention:

1. A thermic telephone comprising a heat conductor and a support Which is in contact with said conductor along substantially the entire length thereof, on one surface of the conductor, the remainder of the conductors surface being exposed to the air, and the said support being a partial conductor of heat but practically a non conductor of electricity.

2. A thermic telephone comprising a heat conductor and a support in contact W1th said conductor along substantially ythe entire length of the conductor, the said support being a partial conductor of heat but practically a non-conductor of electricity.

3. A thermic telephone comprising a support which is a partial conductor of heat but practically a non-conductor of electricity, and a heating conductor of such delicate na ture that it could not preserve its shape unsupported, said conductor, for substantially its entire length, being in contact with said support.

Ll. A thermic telephone comprising a support which is a partial conductor of heat but practically a non-conductor of elec-` tricity, and heating conductor of thin metallic foil in intimate contact with said support. l

5. A thermic telephone comprlsin a support which is a partial conductor of eat but 7. A thermic telephone comprising a delicate heating conductor and a support composed of a metallic body anda surface film of a material which will allow heat to pass to said metallic body, but practically a non conductor of electricity, said heatln ductor being in contact with saidv lm so that the heat from the conductor may pass through the hlm to the body, While shortcircuiting is prevented.

8. A thermic telephonev comprising a support composed of a metallic body and a surface coating which is a fair conductor of heat but a poor conductor of electricity, and a delicate heating conductor which in substanizo tially its entire length is engaged and supported by said surface coating. 4

ln testimony whereof ll have signed this specification.

ROBERT AEENOUT BARON VAN LYNDEN. 

